1. Field of the Invention
The present invention relates to a friction-type continuously variable transmission.
2. Description of the Related Art
Continuously variable transmissions including a plurality of planetary rollers have been known (for example, JP-A 2011-231929). In a continuously variable transmission described in JP-A 2011-231929, a plurality of balls are distributed on a plane perpendicular to a shaft. Each ball makes contact with an input disk on one side, and makes contact with an output disk on an opposite side, and a torque is transferred from the input disk to the output disk (134) through the balls.
Each ball includes a ball shaft capable of inclination, and the speed ratio between the input disk and the output disk can be adjusted by varying the inclination angle of the ball shaft with respect to the shaft. The balls are supported by a pair of arms such that each ball is capable of inclination. The pair of arms, which support both ends of the ball shaft, are both attached to a speed change roller. Accordingly, the speed ratio between the input disk and the output disk is varied when the speed change roller is displaced along the shaft, varying the inclination angle of the ball shaft with respect to the shaft.
Such a known continuously variable transmission as described above has a complicated transmission mechanism, and therefore has problems in a large number of parts and an increased weight, and additionally in difficulty in reducing a production cost.